A while since I have bought one of these! Hero 4 black was the last one when 4K and slow motion came to play and the Gopro 1, 2 and 3 before that.
The Gopro hero 7 Black looks like the best advance in these in a long time. I had noticed filming on a boat this summer in rough seas on the way to St Kilda that my mate with the Gopro hero 6 black was getting much better footage than me with the little stabiliser inside the 6. My hero 4 was just bouncy, jerky and poor as the boat slammed the waves.
Obviously gimbals like my DJI Osmo wouldn't like salt water at all and waves occasionally came over and there was constant spray.
This new Gopro 7 black seems to have very advanced stabilisation inside so I thought I'd give it a go:) I will see how it does, I do have high hopes.